The present invention relates to a rotor and a motor.
Conventionally, a rotor of a Lundell type structure has been known, which is of a permanent magnetic field system. See Japanese Laid-Open Utility Model Publication No. 5-43749, for example. The rotor includes a plurality of pairs of (e.g., two pairs of) magnetic pole plates and permanent magnets, each sandwiched between a pair of the magnetic pole plates. Each pair of magnetic pole plates includes a disk portion and a plurality of flange portions arranged in the circumferential direction of the rotor, and each pair of magnetic pole plates are combined with each other. Adjacent flange portions of the permanent magnet have different magnetic poles. The magnetic pole plates of each pair are arranged such that the disk portions of the same polarities are in contact with each other. In the case of two pairs of magnetic pole plates for example, two disk portions corresponding to north poles are located on both ends of the rotor in its axial direction, and two disk portions corresponding to south poles are located adjacent to each other in the axial direction.
A motor including the above described rotor is desired for improved performance (e.g., increased power). However, the magnetic flux density of the flange portion is affected by the position of the magnetic pole plate. Hence, the rotor is required to reduce variation in magnetic flux density.